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printrboard MINTEMP issue

Posted by floee 
printrboard MINTEMP issue
December 23, 2015 05:46AM
Hey Forum,

Im printing with my makemendel rapidbot 2.0 now for quite some time. And recently it starts giving me some troubles.

I had a broken connection on the hotend. And now that i fixed that the Thermistor on hte hotend is giving me a 0° reading.

I use the same thermistor for bed and hotend. The thermistor on the bed is working fine, giving me a read of about 23°. Once i plug it in the Hotend pin it gives me a 0° reading.

So im asuming its not an issue of the thermistor or the wiring.

-Then i reflashed the software,

-checked the pins on the board

-measured voltage on the board. Both pins measure 4,50V

Anyone has a clue what it could be?

Thanks Floe.

Edited 1 time(s). Last edit at 12/23/2015 05:51AM by floee.
Re: printrboard MINTEMP issue
December 24, 2015 12:46AM
Sounds like the ADC on the controller is dead....

0c normally means its a open cct, since you have already checked the cables and thermistor your left with the main chip.. sadly its not replaceable, and there are no spare thermistor plugs on this particular board.

You need to replace you board or get creative and hack a thermistor onto an expansion pin plus resistor and cap, and update your firmware pins to match (this is not that difficult)

There are two analog pin on the exp1 connector, pins 2 and 4 are A2 and A3 (if your not already using them for something like a LCD) GND and +5 are also conveniently on this connector. If you are using this connector for something else... you need to replace the board.

If you take a look at [reprap.org] you will see the thermistor section, you need to replicate that on either A2 or A3
Re: printrboard MINTEMP issue
December 24, 2015 03:52AM
Hey Dust,

Thanks for your reply.

Thats what i thought it would be! That sucks!

I already changed my REV D board about 3 months ago, because i had an issue with the usb connector pin.

So i'll try to change to another pin after christmas.
Im not really a pro in code, but i'll let you know how it went.

Thanks for the support,
Re: printrboard MINTEMP issue
December 31, 2015 01:39PM
Hey guys thanks for your help,

i tried changing the pn number in the marlin declarations.

Im trying to change the (broken) T-EXT termistor pin to one of the Pins on the EXT2-socket. First of all is it possible to just use 2 pins of the 12 pin EXT 2 or do i need to find another open socket.

Second i dont know how to read the schematics. Now in marlin pins.h the pin 6 is declared for the TEMP_0_PIN


i guess the analog input number is not the number in the schematics (6 = a usb contact) (10 for the bed thermistor = Y-STOP)

can someone help me out?

Thanks in advance,


here's the board: [i63.tinypic.com]

and the schematics for my revD printrboard [reprap.org]

Edited 1 time(s). Last edit at 12/31/2015 01:40PM by floee.
Re: printrboard MINTEMP issue
January 01, 2016 03:03AM

Not sure where you are seeing pin 6

From [github.com]

#define TEMP_0_PIN 1 // Extruder / Analog pin numbering
#define TEMP_BED_PIN 0 // Bed / Analog pin numbering

bed thermistor PF0-ADC0 0
hotend thermistor PF1-ADC1 1

so an educated guess would be pins 2 and 3

A2 PF2-ADC2 2
A3 PF3-ADC3 3

Regarding the thermistors, you need 3 pins 5V, A2 (or A3) and GND

picpaste keeps changing the url.. might have to go to [picpaste.com] to see it.

So you also need a 4.7k 1% resistor and a 10nf capacitor

Edited 5 time(s). Last edit at 01/02/2016 10:50PM by Dust.
Re: printrboard MINTEMP issue
January 02, 2016 01:38PM
Hey Dust,

Thanks for your help.

The pin declaration im using (and was working for 2 years) is following:

#define HEATER_0_PIN 13
#define HEATER_1_PIN -1
#define HEATER_2_PIN -1
#define TEMP_0_PIN 6
#define TEMP_1_PIN -1
#define TEMP_2_PIN -1
#define HEATER_BED_PIN 4
#define TEMP_BED_PIN 10

if i read the schematics right it makes no sense to me too, but this is part of the firmware provided to my rapidbot 2.0 by makemendel. And i had it working for years like that. I also double checked, if i changed something on accident.

So i decided to try the version suggested by you. I got the capacitator and the resistor needed.

Now in your sketch (thanks for that by the way) I assume I have to connect to only one pin:
like that :
01 [i66.tinypic.com]

if i read the schematics right i would connect 2 pins,that way:
02 [i64.tinypic.com]

sorry for me asking so much, but im an architect and not that common with electronics

Re: printrboard MINTEMP issue
January 02, 2016 10:47PM
If its the same as the v3 I can see

pins.h contains definitions for several boards

In configuration.h find the line #define MOTHERBOARD
It should be set to 81 for printrboard

then in pins.h look for the section that starts with == 81

In the version I have this starts
* Teensylu 0.7 / Printrboard pin assignments (AT90USB1286)
* Requires the Teensyduino software with Teensy++ 2.0 selected in Arduino IDE!
* See [reprap.org] for more info

in that section it says
#define TEMP_0_PIN 1 // Extruder / Analog pin numbering
#define TEMP_BED_PIN 0 // Bed / Analog pin numbering
Re: printrboard MINTEMP issue
January 02, 2016 10:54PM
First picture, is all you need, those 3 wires to the 3 pins on the extension port

Second picture your grounding A3? no need to do this.

Edited 1 time(s). Last edit at 01/02/2016 10:56PM by Dust.
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